nulagrithom's answer was really good and true but here's maybe a simpler way to put it: "planned work" is really "prioritized and agreed to" work. "ad-hoc" wor

nulagrithom's answer was really good and true but here's maybe a simpler way to put it: "planned work" is really "prioritized and agreed to" work. "ad-hoc" work is just the urgent priority of (usually) one person. After years of dealing with the conflict, I've found the easiest answer is always "I'd be happy to give you what you need. Which of these planned tasks from you (or your boss) are you willing to sacrifice or postpone for your urgent task?" 80% of the time that's enough. If not, you walk them over to their boss and ask them the same question. Then, you can go back to your desk and work and let them hash it out or hash it out with your boss to convert this "ad-hoc" request into a "agreed to, planned request."